CDN resolving


My ISP is discouraging its users from using or etc. They say CDN resolving (Akamai etc) is “suboptimal” with these services because they may give out incorrect IP addresses not based on your location.

What’s the deal here? Does respect the GEO of the user and still provide optimal IP’s somehow for other CDN’s?


I am not aware that there are problems.

If you execute
dig @ id.server chaos txt

It will return a location. fra03 for Frankfurt for example.

ok, seems that…
Have a look at this:

#3 has made lots of effort to pass (part of) client’s IP to the authoritative servers if they support it. EDIT: for, they should be relatively close to you, thanks to CloudFlare having so many PoPs, so I expect the answers will be almost always the best you can get anyway.


So you mean because I get routed to a datacenter near me, which in turn should get IP records for other CDN’s “near it”, I should be fine?

Yes, gets routed “fairly” close to me, but not 100% optimal (I get routed to FRA instead of ZRH, I have actually tweetet my ISP asking why… they both peer at SwissIX and could go “in-country”)


Yes, that’s what I meant. There’s a tradeoff between privacy and optimality. CloudFlare is more on the privacy side, as only their CDN IP is “leaked” upstream. Google is more on the optimality side.

Beware that fastest route is only loosely connected to geographical closeness, and there are also other considerations.